High end hesitation + gutless feeling

[krystalized_jdm]

[Like the title says

For the record, my feeling of my car being slower then normal is I've seen another skyline w/ an oem rb20 pull alot faster then I do.

Car tends to sound like a misfire at high rpm (about 5k+) Typically only at about 75%+ throttle if I slightly hold it down, and hit right to 5k+ it usually doesn't do it. Could this be a sign of bad compression?

Lately (Since the pod filter + BOV) car seems to feel gutless and alot slower (This also goes hand in hand w/ the above question, it may NOT be from either) Could these on oem engine + tune be fine? I've heard of everyone saying that every bolt on is fine.... but not sure why it's doing this.

What would you guys recommend to CHECK and/or change to fix these problems?

[Skym]

Fit new colder heat range (heat range 6) NGK copper sparkplugs (stock is PFR5A-11 = heatrange 5, platinum tip, 1.1mm gap), regapped to 0.8mm. Only problem is have to change copper sparkplugs earlier (every 10,000km or so vs 100,000km with stock platinum tip sparkplugs).

[Dragon Humper]

Yea, that sounds like a lean misfire, which is what you would get at 75% throttle. Do the plugs for sure and also change your fuel filter if you haven't already. A slight leaning might not be that apparent at WOT but will show up at a part throttle position because the fuel map will be much richer at WOT masking the leanout.


Jon.

[krystalized_jdm]

Yes, both of what you said and what SKYM said to me via PM to another few questions 100% clarify my situation.

The thing that really stuck out was him saying

"If engine has missed at higher rpm due to too wide sparkplug gap, expect coilpacks to fail. 2x coilpacks failed on my cars engine, cylinder 4, 5 coilpacks from memory"

- I replaced all 6 coilpacks BRAND new about 2 1/2 years ago. I've already had one fail. So I can see that

He also said "With higher boost level than stock it might have affected sparkplugs (blowing spark out at higher rpm with stock 1.1mm gap on sparkplugs), hence missing sound at 5000rpm+ that could make ECU switch to knock maps which pulls ignition timing, injects more fuel"

- Which also makes ALOT of sense. My car tanks on gas, to the point where driving about 5-6 km's x2 to college and back everyday was costing me 20-25 bucks in gas. (With going NOWHERE else, and there is never traffic in my city)

Anyways, I'll be returning to stock airbox and BOV.

Thanks for the response guys.

[r33_gtst]

Stock airbox and bov?
Why?

[krystalized_jdm]

I've never used oem aribox and an aftermarket bov. I had a pod filter + bov and oem bov delete.

I can verify the pod filter + extra boost being the issue.

Put the oem airbox on and did some 2nd/3rd gear pulls and she stayed strong right till 6k ( I won't go higher, I try to baby it =P)

Thanks for the input guys.

[hp44incgtr]

i have the same problem i just install brand new gt28-5...

[krystalized_jdm]

There's a thread I actually found this morning before I made my engine back to oem. I believe it's called fix your hesitation, but I'm n ot 100% sure if it'll exactly apply to your turbo upgrade....

Hope you figure it out b. GL

[hp44incgtr]

yea thanks B this car make me depress i just put 3500 bones in it turbo and clutch and its still not running well.. hope you get yo problem fix 2..

[Skym]

Yes, both of what you said and what SKYM said to me via PM to another few questions 100% clarify my situation.

"hence missing sound at 5000rpm+ that could make ECU switch to knock maps which pulls ignition timing, injects more fuel"

It's only a guess that it might switch to knock maps at 5000rpm+ (missing = high knock count). Most say stock ECU (RB20DET) looks for knock between 1000rpm-3500rpm, so it might not switch to knock maps if missing happens after 3500rpm (engine gets too noisey, so hard to determine if it's knock or not). Same applies to most stock ECU's that work the same way (except different window settings, 1000rpm-3500rpm is for RB20DET engine, tune).

Also you said diesel was run through engine, so might be some diesel still in fuel system, even if did drop fuel tank and drain tank, refilled with new fuel. Changing fuel filter is a way to make sure clogged fuel filter is not a cause of a lean A/F ratio. Most never change fuel filter. Fuelfilter is meant to be changed every 20,000km or less.

[krystalized_jdm]

I will look into buying a new fuel filter.

Thank you skym

[ToroGTS]

Get the fuel filter for a 300zx and ditch the stock gts-t filter mounting bracket, I just zip tied mine to some vac lines and was good to go. Pull your neg battery terminal before you do the work so you are on fresh ECU learn once you get proper fuel flow.

[Voodoo_ChildR32]

Get the fuel filter for a 300zx and ditch the stock gts-t filter mounting bracket, I just zip tied mine to some vac lines and was good to go. Pull your neg battery terminal before you do the work so you are on fresh ECU learn once you get proper fuel flow.

Or use the infinity j30 filter, 96 I think. It's a direct drop in, no mods required.


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